Hello @connochaetes
You may first disable the built-in keyboard:
To do this, go to "Settings" > "Devices" > "Touchpad" and make sure the toggle switch for "Touchpad" is turned off. This will disable the built-in keyboard and touchpad on your device in tablet mode, allowing you to use your wireless keyboard instead.
Also check if the wireless keyboard is paired with your Acer TravelMate Spin. Go to "Settings" > "Devices" > "Bluetooth & other devices" and check if your wireless keyboard is listed under "Other devices"